1. Field of the Invention
The present invention relates to a non-contact type moving table used with, for example, a bonding machine for manufacturing semiconductor devices.
2. Prior Art
Conventionally, moving tables that use compressed air as shown in FIGS. 23 and 24, and those that use a combined compressed air/magnetic system as shown in FIG. 25, are used as non-contact type single-axis moving tables that are employed in, for example, a semiconductor device manufacturing apparatus.
The compressed air system shown in FIG. 23, that shows the top view thereof, includes a guide table, 80 which has four guide surfaces 80a, 80b, 80c and 80d on each side (top, bottom, left and right in the drawing), and a moving table 81 which has moving surfaces 81a, 81b, 81c and 81d that are separated from the guide surfaces 80a, 80b, 80c and 80d with a gap (or an air gap) of several microns in between.
Compressed air is blown in the directions as shown by arrows 82 against the guide surfaces 80a through 80d of the guide table 80 from the moving surfaces 81a through 81d of the moving table 81. As a result, the moving table 81 floats on the guide table 80, thus forming a non-contact type single-axis moving table.
If an external force is put on the moving table 81 from above the table 81 (or in a direction perpendicular to the surface of the drawing paper), the moving table 81 is moved (without contact) in a single direction relative to the upper surface of the table 80.
On the other hand, the compressed air system shown in FIG. 24, which shows the side view thereof, includes a guide table 87, which has guide parts 85 and 86, and a moving table 88.
The guide part 85 has guide surfaces 85a, 85b and 85c on its upper, lower and left-end surfaces, and the guide part 86 has guide surfaces 86a, 86b and 86c on its upper, lower and right-end surfaces.
The moving table 88 has moving surfaces 88a, 88b, 88c, 88d and 88e which are separated from (or are in non-contact with) the guide surfaces 85a, 85b, 85c, 86a, 86b and 86c with a gap of several microns.
Compressed air is blown in the directions shown by arrows 89 against the guide surfaces 85a, 85b, 85c, 86a, 86b and 86c of the guide table 87 from the moving surfaces 88a through 88e of the moving table 88. As a result, the moving table 88 is caused to float, thus forming a non-contact type single-axis moving table.
Accordingly, if an external force is applied to the moving table 88 from the side (or applied in a direction perpendicular to the surface of the drawing), the moving table 88 is moved laterally (without contact) in a uniaxial direction (or in a perpendicular direction relative to the drawing paper).
FIG. 25 shows the side of the combined compressed air/magnetic system. In this system, the lower section used in the system shown in FIG. 24 is modified.
More specifically, permanent magnets 90 and 91 are installed on the undersurface of a moving table 88, and permanent magnets 92 and 93 which have magnetic poles that attract the permanent magnets 92 and 93 are installed on a guide table 87.
In this system, compressed air is blown in the directions as shown by arrows 89 against the guide surfaces of the guide table 87 from the moving table 88. When the air is thus blown, mutual repulsion is produced by the compressed air blown in the horizontal direction, so that horizontal rigidity is obtained; and in the vertical direction, mutual repulsion is produced by the compressed air and this repulsion is balanced by the attractive force of the permanent magnets 90, 91, 92, and 93, so that vertical rigidity is obtained. Thus, a non-contact type single-axis moving table is obtained in this system, too.
In the prior art described above, a plurality of surfaces are restrained by means of compressed air or by means of compressed air and permanent magnets in order to obtain rigidity and tensile rigidity in the vertical direction. More specifically,
a. in the case of the system shown in FIG. 23, two surfaces above and two surfaces below, that is, (1) the guide surface 80a and the moving surface 81a, and (2) the guide surface 80b and the moving surface 81b, are restrained;
b. in the case of the system of FIG. 24, four surfaces above and four surfaces below, that is, (1) the guide surface 85a and the moving surface 88a, (2) the guide surface 86a and the moving surface 88a, (3) the guide surface 85b and the moving surface 88b, and (4) the guide surface 86b and the moving surface 88d, are restrained; and
c. in the case of the system of FIG. 25, four surfaces above and four surfaces below, that is, (1) the guide surface 85a and the moving surface 88a, (2) the guide surface 86a and the moving surface 88a, (3) the permanent magnets 90 and 92, and (4) the permanent magnets 91 and 93, are restrained.
On the other hand, if a single-axis moving table is to be created, it is necessary to restrain two surfaces on the left and two surfaces on the right. In other words,
a. in the system of FIG. 23, (1) the guide surface 80c and the moving surface 81c, and (2) guide surface 80d and moving surface 81d, and
b. in the systems shown in FIGS. 24 and 25, (1) the guide surface 85c and the moving surface 88d, and (2) the guide surface 86c and the moving surface 88e,
are restrained by means of the compressed air in order to obtain pressing rigidity and tensile rigidity in the left-right direction in addition to the above-described pressing rigidity and tensile rigidity in the vertical direction.
As seen from the above, at least four surfaces (top, bottom, left and right) are required. Furthermore, in order to create an XY table (which is a biaxial moving table), it is necessary to use two single-axis moving tables and combine them so that the moving tables are installed perpendicular to each other.
In the above prior arts, the number of the necessary surfaces is large. In addition, it is necessary to maintain an extremely small air gap of a few microns between the facing surfaces. Accordingly, high finishing precision is required, and assembly and adjustment of the device are extremely difficult, which results in high manufacturing costs. Furthermore, since the number of the surfaces is large, the moving table is also large in size, weight and complexity, which also causes the higher costs. In addition, since the air gap is extremely small, the effect of thermal expansion becomes large. Thus, the materials which are suitable for the device are limited.